﻿/*
// jQuery Ajax File Uploader
//
// @author: Jordan Feldstein <jfeldstein.com>
//
//  - Ajaxifies an individual <input type="file">
//  - Files are sandboxed. Doesn't matter how many, or where they are, on the page.
//  - Allows for extra parameters to be included with the file
//  - onStart callback can cancel the upload by returning false
*/


(function ($) {
    $.fn.ajaxfileupload = function (options) {
        var settings = {
            params: {},
            action: '',
            onStart: function () { },
            onComplete: function (response) { },
            onCancel: function () { },
            validate_extensions: true,
            valid_extensions: ['gif', 'png', 'jpg', 'jpeg'],
            submit_button: null
        };

        var uploading_file = false;

        if (options) {
            $.extend(settings, options);
        }


        // 'this' is a jQuery collection of one or more (hopefully) 
        //  file elements, but doesn't check for this yet
        return this.each(function () {
            var $element = $(this);

            // Skip elements that are already setup. May replace this 
            //  with uninit() later, to allow updating that settings
            if ($element.data('ajaxUploader-setup') === true) return;

            $element.change(function () {
                // since a new image was selected, reset the marker
                uploading_file = false;

                // only update the file from here if we haven't assigned a submit button
                if (settings.submit_button == null) {
                    upload_file();
                }
            });

            if (settings.submit_button == null) {
                // do nothing
            } else {
                settings.submit_button.click(function (e) {
                    // Prevent non-AJAXy submit
                    e.preventDefault();

                    // only attempt to upload file if we're not uploading
                    if (!uploading_file) {
                        upload_file();
                    }
                });
            }

            var upload_file = function () {
                if ($element.val() == '') return settings.onCancel.apply($element, [settings.params]);

                // make sure extension is valid
                var ext = $element.val().split('.').pop().toLowerCase();
                if (true === settings.validate_extensions && $.inArray(ext, settings.valid_extensions) == -1) {
                    // Pass back to the user
                    settings.onComplete.apply($element, [{ status: false, message: 'The select file type is invalid. File must be ' + settings.valid_extensions.join(', ') + '.' }, settings.params]);
                } else {
                    uploading_file = true;

                    // Creates the form, extra inputs and iframe used to 
                    //  submit / upload the file
                    wrapElement($element);

                    // Call user-supplied (or default) onStart(), setting
                    //  it's this context to the file DOM element
                    var ret = settings.onStart.apply($element, [settings.params]);

                    // let onStart have the option to cancel the upload
                    if (ret !== false) {
                        $element.parent('form').submit(function (e) { e.stopPropagation(); }).submit();
                    } else {
                        uploading_file = false;
                    }
                }
            };

            // Mark this element as setup
            $element.data('ajaxUploader-setup', true);

            /*
            // Internal handler that tries to parse the response 
            //  and clean up after ourselves. 
            */
            var handleResponse = function (loadedFrame, element) {
                var response, responseStr = $(loadedFrame).contents().text();
                try {
                    //response = $.parseJSON($.trim(responseStr));
                    response = JSON.parse(responseStr);
                } catch (e) {
                    response = responseStr;
                }

                // Tear-down the wrapper form
                element.siblings().remove();
                element.unwrap();

                uploading_file = false;

                // Pass back to the user
                settings.onComplete.apply(element, [response, settings.params]);
            };

            /*
            // Wraps element in a <form> tag, and inserts hidden inputs for each
            //  key:value pair in settings.params so they can be sent along with
            //  the upload. Then, creates an iframe that the whole thing is 
            //  uploaded through. 
            */
            var wrapElement = function (element) {
                // Create an iframe to submit through, using a semi-unique ID
                var frame_id = 'ajaxUploader-iframe-' + Math.round(new Date().getTime() / 1000)
                $('body').after('<iframe width="0" height="0" style="display:none;" name="' + frame_id + '" id="' + frame_id + '"/>');
                $('#' + frame_id).get(0).onload = function () {
                    handleResponse(this, element);
                };

                // Wrap it in a form
                element.wrap(function () {
                    return '<form action="' + settings.action + '" method="POST" enctype="multipart/form-data" target="' + frame_id + '" />'
                })
                // Insert <input type='hidden'>'s for each param
                .before(function () {
                    var key, html = '';
                    for (key in settings.params) {
                        var paramVal = settings.params[key];
                        if (typeof paramVal === 'function') {
                            paramVal = paramVal();
                        }
                        html += '<input type="hidden" name="' + key + '" value="' + paramVal + '" />';
                    }
                    return html;
                });
            }
        });
    }
})(jQuery)
